Some of the biggest galaxies in the universe are full of extinguished stars. But nearly 12 billion years ago, soon after the universe first was created, these massive galaxies were hotspots that brewed up stars by the billions. How these types of cosmic realms, called dusty starburst galaxies, became galactic dead zones is an enduring mystery. Astronomers at the University of Iowa, in a new study published in the Astrophysical Journal, offer a clue. They say quasars, powerful energy sources believed to dwell at the heart of galaxies, may be responsible for why some dusty starburst galaxies ceased making stars.